| Message ID | 1452592736-6463-2-git-send-email-paul.durrant@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 2016-01-12 at 09:58 +0000, Paul Durrant wrote: > My previous patch 03809ae7 "document transmit and receive wire formats > separately" improved documentation of the receive and transmit wire > formats but further clarifications were requested. > > This patch adds those clarifications. > > Signed-off-by: Paul Durrant <paul.durrant@citrix.com> Acked-by: Ian Campbell <ian.campbell@citrix.com> > Cc: Ian Jackson <ian.jackson@eu.citrix.com> > Cc: Jan Beulich <jbeulich@suse.com> > Cc: Keir Fraser <keir@xen.org> > Cc: Tim Deegan <tim@xen.org> > --- > > v6: > - v4 of the original patch was committed so this is an > incremental version of the patch in v5. > > v5: > - Add extra clarifications. > --- > xen/include/public/io/netif.h | 28 ++++++++++++++++++++++++---- > 1 file changed, 24 insertions(+), 4 deletions(-) > > diff --git a/xen/include/public/io/netif.h > b/xen/include/public/io/netif.h > index 1790ea0..0a3272f 100644 > --- a/xen/include/public/io/netif.h > +++ b/xen/include/public/io/netif.h > @@ -154,19 +154,29 @@ > * Guest transmit > * ============== > * > - * This is the 'wire' format for packets: > + * This is the 'wire' format for transmit (frontend -> backend) packets: > + * > * Fragment 1: netif_tx_request_t - flags = NETTXF_* > * size = total packet size > * [Extra 1: netif_extra_info_t] - (only if fragment 1 flags include > * NETTXF_extra_info) > + * ... > * [Extra N: netif_extra_info_t] - (only if extra N-1 flags include > * XEN_NETIF_EXTRA_MORE) > * ... > * Fragment N: netif_tx_request_t - (only if fragment N-1 flags > include > - * NETTXF_more_data) > + * NETTXF_more_data - flags on > preceding > + * extras are not relevent here) > * flags = 0 > * size = fragment size > * > + * NOTE: > + * > + * This format slightly is different from that used for receive > + * (backend -> frontend) packets. Specifically, in a multi-fragment > + * packet the actual size of fragment 1 can only be determined by > + * subtracting the sizes of fragments 2..N from the total packet size. > + * > * Ring slot size is 12 octets, however not all request/response > * structs use the full size. > * > @@ -202,19 +212,29 @@ > * Guest receive > * ============= > * > - * This is the 'wire' format for packets: > + * This is the 'wire' format for receive (backend -> frontend) packets: > + * > * Fragment 1: netif_rx_request_t - flags = NETRXF_* > * size = fragment size > * [Extra 1: netif_extra_info_t] - (only if fragment 1 flags include > * NETRXF_extra_info) > + * ... > * [Extra N: netif_extra_info_t] - (only if extra N-1 flags include > * XEN_NETIF_EXTRA_MORE) > * ... > * Fragment N: netif_rx_request_t - (only if fragment N-1 flags > include > - * NETRXF_more_data) > + * NETRXF_more_data - flags on > preceding > + * extras are not relevent here) > * flags = 0 > * size = fragment size > * > + * NOTE: > + * > + * This format slightly is different from that used for transmit > + * (frontend -> backend) packets. Specifically, in a multi-fragment > + * packet the size of the packet can only be determined by summing the > + * sizes of fragments 1..N. > + * > * Ring slot size is 8 octets. > * > * rx request (netif_rx_request_t)
diff --git a/xen/include/public/io/netif.h b/xen/include/public/io/netif.h index 1790ea0..0a3272f 100644 --- a/xen/include/public/io/netif.h +++ b/xen/include/public/io/netif.h @@ -154,19 +154,29 @@ * Guest transmit * ============== * - * This is the 'wire' format for packets: + * This is the 'wire' format for transmit (frontend -> backend) packets: + * * Fragment 1: netif_tx_request_t - flags = NETTXF_* * size = total packet size * [Extra 1: netif_extra_info_t] - (only if fragment 1 flags include * NETTXF_extra_info) + * ... * [Extra N: netif_extra_info_t] - (only if extra N-1 flags include * XEN_NETIF_EXTRA_MORE) * ... * Fragment N: netif_tx_request_t - (only if fragment N-1 flags include - * NETTXF_more_data) + * NETTXF_more_data - flags on preceding + * extras are not relevent here) * flags = 0 * size = fragment size * + * NOTE: + * + * This format slightly is different from that used for receive + * (backend -> frontend) packets. Specifically, in a multi-fragment + * packet the actual size of fragment 1 can only be determined by + * subtracting the sizes of fragments 2..N from the total packet size. + * * Ring slot size is 12 octets, however not all request/response * structs use the full size. * @@ -202,19 +212,29 @@ * Guest receive * ============= * - * This is the 'wire' format for packets: + * This is the 'wire' format for receive (backend -> frontend) packets: + * * Fragment 1: netif_rx_request_t - flags = NETRXF_* * size = fragment size * [Extra 1: netif_extra_info_t] - (only if fragment 1 flags include * NETRXF_extra_info) + * ... * [Extra N: netif_extra_info_t] - (only if extra N-1 flags include * XEN_NETIF_EXTRA_MORE) * ... * Fragment N: netif_rx_request_t - (only if fragment N-1 flags include - * NETRXF_more_data) + * NETRXF_more_data - flags on preceding + * extras are not relevent here) * flags = 0 * size = fragment size * + * NOTE: + * + * This format slightly is different from that used for transmit + * (frontend -> backend) packets. Specifically, in a multi-fragment + * packet the size of the packet can only be determined by summing the + * sizes of fragments 1..N. + * * Ring slot size is 8 octets. * * rx request (netif_rx_request_t)
My previous patch 03809ae7 "document transmit and receive wire formats separately" improved documentation of the receive and transmit wire formats but further clarifications were requested. This patch adds those clarifications. Signed-off-by: Paul Durrant <paul.durrant@citrix.com> Cc: Ian Campbell <ian.campbell@citrix.com> Cc: Ian Jackson <ian.jackson@eu.citrix.com> Cc: Jan Beulich <jbeulich@suse.com> Cc: Keir Fraser <keir@xen.org> Cc: Tim Deegan <tim@xen.org> --- v6: - v4 of the original patch was committed so this is an incremental version of the patch in v5. v5: - Add extra clarifications. --- xen/include/public/io/netif.h | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-)